Thread-breaking mechanism



Apr. 3, 1923. I 1,450,531

J. P. WEIS THREAD BREAKING MECHANISM Original Filed Oct. 16; 1914 2 sheets-sheet '1 Apr. 3, 1923.

J. P. WEIS THREAD BREAKING MECHANISM 2 sheets-sheet 2 Original Filed 001;. 16, 1914 INVENTOF BY John 7? W215.

Patented Apr. 3, 1923.

umrro STATES 1,450,561 PATENT OFFICE.

JOHN PETER WEIS, or NYacK, NEW YORK, ass euo'a or ONE-HALF .TO ivin'r'aoroiii- TAN SEWING MACHINE CORPORATION, or novEn, DELAWARE, a o'oaronA'rIoN OF DELAWARE.

THREAD-BREAKING MECHANISM.

Original application filed October 16, 1914, Serial No. 867,005. Renewed December 24, 1919, Serial Nb. 347,189. Patent No. 1,346,526, dated August 3, 1920. Divided and this application filed January 2',

1919. 'Serial N0. 269,277.

To all whom it may concern:

Be it known that 1, JOHN PETER W'nrs, a citizen of the United States, residing at Nyack, in the county of Rookland and Stat-e of. New York, have invented certain new and useful Improvements in Thread-Breaking Mechanisms, of which the following is specification.

This invention relates to thread-breaking mechanism for sewing machines especially, and is especially useful in bodily-moving sewing-machine heads. This application is a division of my application Serial No. 867,005, filed October 16, 191 1, renewed Deceinber 2d, 1919, Serial No. $417,189, and patented August 3, 1920', No; 1,348,526, and shows -the weighted crank and pitman needle-drive together with the automatically adjusting wo1'k-holding foot mechanisms shown in my application Serial No. 269,273, filed January 2, 1919, on which Patent No. 1,419,087 was granted June 6,1922, and which latter application is also a division of said application Serial No 867,005 on which said 2 Patent No. 1,348,526 was issued.

In the accompanying drawings forming a part hereof,

Fig. 1 is a perspective view of the frpnt end of a sewing-machine head embodylng this invention.

Fig. 2 is an end view of the throat-plate work-holding foot, looper and looper thread pull-off slide and thread-breaking mechanisi'ns assembled, the needle being also shown.

Fig. 3 is a top plan view of the throat plate; and shows the looper thread pull off slide in two positions, the full line position indicating its operative and the dotted line position indicating its inoperativeposition.

Fig. 4: is a perspective view of the looper thread pull ofi slide.

Fig. 5 is an end elevation of what is shown in Fig. 3 looking in the direction of the arrow.

I Figs. 6 and 7 are partial sectional views of the thrbat-plate, looper thread pull off slide and looper thread finishing plate carried by. the'throa-t-plate, both figures at sec tion line 6 f Fig 5 looking in the direction of the arrow shown in Fig. 5, and illufstrat the loope'r in di'fier'ent positions-operatingpn therlooper thread. Fig. 6 shows the thread pull off slide in its operative position during the stitching and Fig. 7 shows the tread pull off slide in thread pull off the needle and l'oop'er threads in working relation to the goods and to one another, the needle being down through the goods and the loop'er in a backward position.

-Fig. 9 is an enlarged view of what is shown in Fig. 7 but with goods in place, the needle and looper threads in working relation one to another and the needle being above the goods and the looper in its most forward position.

Herein the yielding work-holding foot is indicated by F, the needle by N, the looper by L, the looper shaft by M, the upper sewing-machine arm by A, and the under arm by A.

The throat plate P carries a lever 1 for actuating a bottom or looper thread pull off slide, the lever being pivoted at2 to an arm 3 of the throat plate which has in its upper surface a slidewa 9 for the pull off slide 5 which at 41 is pivoted to an end of lever 1. The front end 6 of the pull off slide has in its forward end portion a needle hole 7 that is elongated rearwardly at 7 The needle hole 8 through the throat plate is formed in the bottom wall of the slideway which is partially covered lengthwise by a looper thread pinch plate 10 that is fixed at 11 to the upper wall of the throat plate. As shown in Fig. 4, half the thickness of the pinch plate 10 is cut away lengthwise of it at one under margin 12 that overhangs the bottom thread pull off slide. The width of the reduced marginal portion'12 is the same as that of the pull off slide; Between its ends, this pinch plate on its underside, is formed with a transverse under or looper thread clamping or pinching l-ip shoulder or vertical wall 13 so as to form a transverse lip 14 of about the width of the pull off slide; and forward of this lip 14: the front end portionl16 of the pinch plate forms a bottom thread breaker plate which is'of the th-icknesfspf the marginal portion 12. Asviewed in Fig. 1, the pinch plate 10 is stepped omits andePsur-faee; and it is securedfhy the fasteners 11 to the upper surface of the throat thread pull off slide plate with the free end of its breaker plate 16 extending forwardly but terminating rearwardly of the needle hole 8 through the throat plate (Figs. 6 and 7). Forthe reason that, in the assemblage, the breakerplate 16 overhangs the pull off slide and is spaced above it, a vertical guard shown in the form of a pin 17 is located at the front end of the breaker plate at one side of the slideway for the purpose of preventing threads or goods from getting in under or hooking on the front end of the breaker plate the executive or work performing end of which is crosswise of the pull off slide.

As shown, the throat plate is provided with a band saw guard 18.

- The mode of operation during stitching is as follows:

The looper thread indicated by a leads from a'source of supply through the back and front eyes of the looper blade in the usual manner, and leads through the front looper eye upwardly through the needle hole 8 of the throat plate and extends thence through the needle hole 7 of the pull off slide; and thence to the last stitch in the goods. The needle thread 6 is carried by the needle downwardly through the needle hole 7 when it is over the needle hole 8 and the needle thread loop is entered by the thread-carrying looper blade as the needle rises; at which time the needle thread loop b is drawn up against the underside of the looper blade. When the needle in its upward movement has been stopped at the end of any stitching operation, the bottom is retracted; the front wall of its needle hole 7 then pulls slack bottom thread rearwardly and against the backwall of the needle hole 8, the upper end of the bottom thread being anchored in the goods which are fed rearwardly by feed rolls (not shown) simultaneously with the retreat of the pull off slide. During such rearward movements of the goods and of the bre'akerslide, the bottom thread is by said rearward movements pulled over the front edge of the breaker plate 16, the bottom thread then running through the needle holes 7 and 8 and the eyes of the looper blade.

The pull of the feed rolls on the goods breaks the needle thread loop across the under edge of the looper blade, and simultane- 'ously, at the completion of the backward movement of the breaker slide, the bottom thread is broken across the breaker plate 16, the bottom thread being at this time pinched between the clamp lip 14 of the pinch plate and the then opposed front marginal Wall portion Q of'the needle hole 7. The inner edge of the throat plate is preferably bent down at 19 to prevent goods and thread from catching on the throat plate. This action of the bent down inner margin of the pinching lip 14.

throat plate is especially important in bodily-movable sewing machines provided with cutting means of the type shown in my said Patent No. 1,848,526 of August 3.

1920 and in. my prior Patent No. 1,114,082,.

It will be observed that the looper thread i a. has three bends in a vertical plane, one bend over the rearward edge of the needle hole in the throat plate, the next or intermediate bend over the forward edge of the breaker slide needle hole, and the third over the forward edge of the breaker plate. At the two end bends the looper thread is in frictional contact with the parts against which they bear, and such "friction causes sufficient restraint on the movement of the thread to permit the breaker slide to move forward without moving the looper thread at the two end bends. Otherwise the thread movement would tend to snarl the thread or otherwise interfere with the proper starting of the stitching; and also to move forward with the walls of the elongation of its needle hole slot 7 loosely straddling the looper thread between the two end bends. If it were not for the elongation of the needle holeslot 7 the thread would be apt to be pinched by the pull oil slide in its forward movement, and so interfere with the feeding of the goods.

The under or looper thread-breaker slide is also a looper thread measuring device because on its backward movement it pulls oil? the required length of under or looper thread for the commencement of the next sewing movements oi the needle and the l0oper;and while the thread is pinched at 15 by the under or looper thread clamping or pinching lip 1.4 it is broken over the end 16 in consequence of the strain of the feed of the goods. the plate 10 is slightly sprung up by the thread drawn between it and the breaker slide.

The'clearances referred toare indicated In the pinching movement by 12" and 16 and they permit the looper thread. to find its intermediate bend to loop around and be drawn under the thread- Referring to the enlarged views of Figs. 8 and 9, Fig. 8 shows the needle down and the looper back and the breaker-slide forward. The needle thread I) has one strand extending in the direction or" the arrow to a thread supply not shown. The free end of the upper strand of the needle thread is adjacent the upper side of the goods, the first descent of the needle in stitching the goods G having occurred. The free end of the looper thread a is adjacent the under side of the goods and out of contact with the breaker-slide and extends up through the elongated opening 7* of the breaker-slide. hen, at the end of a seaming operation, as indicated by Fig. 8, the needle stops in its upper position above the goods, the looper is forward through the needle thread loop and the free end of the needle thread strand instead of being up through the goods has been broken at the under side of the goods by the'operation of the feed of the goods and appears adjacent the under side of the goods. After the needle has stopped in its up position the breaker-slide moves rearwards into the position shown in Fig. 9 and the looper thread is broken over to the edge of the pinch plate, as above described; the free end. of the looper thread then being in the position shown in Fig. 9. After the end of the sewing operation, above referred to, any further feed of the goods will obviously pull the free end of the needle thread strand out of the position shown in Fig. 7 and such free end will be carried by the operation of the machine into a position above the goods where, at the beginning of a second sewing operation, the positions of the parts shown in Fig 8 will be repeated.

What I claim is,

1. Thecombination in a sewing machine. of stitch-forming instrumentalities, a throat plate, and thread-breaker mechanism carried by the throat plate, said thread breaker mechanism comprising a slide formed with an elongated needle hole; a stationary thread breaker plate located in the path of the looper thread to be broken; and the throat plate having a needle hole with which the needle hole through the slide is registrable; and a thread carrying looper.

2. In the structure of claim 1, the threadbreaker mechanism comprising a throat plate having a thread clearance rearward of the needle hole; a plate'fixed to the throat plate to keep the breaker slide in place, the plate having on its inward side a transverse under thread clamping lip cooperating with the front end of the breaker slide to clamp the thread.

3. In the structure of claim 1, the threadbreaker mechanism comprising a throat plate having a thread clearance rearward of the needle hole; a plate fixed to the throat plate to keep the breaker slide in place, the plate having on its inward side a transverse under thread clamping lip cooperating with the front end of the breaker slide to clamp the thread; and a guard for the mouth of the clearance.

4. The combination of a throat plate having a needle hole; a thread carrying looper; a stationary looper thread breaker; a pull off slide having an elongated needle eye; and a yielding looper thread pinch plate having a looper thread pinching lip.

5. The combination with a sewing mechanism comprising a needle; a looper; a presser-foot and a throat plate having a. needle eye through it of a reciprocating slide mounted in a guide-Way at the upper surface of the throat plate, the front end of the slide forming a looper thread breaker; a stationary pinch plate covering the slide in the guide-way and forming a looper thread pinching member, the slide having an elongated needle slot extending lengthwise of it.

In testimony whereof I have hereunto set my hand this 27th day of December, 1918.

JOHN PETER WEIS. 

